1. Field of the Invention
The present invention relates to a substrate treatment technique of treating a substrate by supplying a substrate with a treatment solution while rotating the substrate.
2. Description of Background Art
As such a substrate treatment technique, Japanese Patent No. 5123122 discloses a substrate treating apparatus that supplies a fluid, preliminarily subjected to temperature control, to a large number of points between the central portion and the edge portion of the substrate and emits a treatment solution to the upper surface of the substrate, thereby treating the substrate. The apparatus includes temperature control units individually controlling the temperatures of the fluids supplied from a large number of points below the substrate. Each fluid is individually subjected to temperature control by a corresponding temperature control unit such that the temperature of the fluid increases as the position of the substrate, which is supplied with the fluid, approaches the edge portion from the central portion of the substrate. This allows the apparatus to reduce a temperature difference of the substrate arising from a difference in the circumferential velocity between the central portion and the edge portion of the substrate, thereby uniformizing the substrate treatments with a treatment solution.
Japanese Patent Application Laid-Open. No. 2012-151439 discloses a substrate treating apparatus including an upper nozzle and a rod-shaped lower nozzle. The upper nozzle is caused to scan the portion between the central section and the peripheral section of the substrate above a circular substrate that rotates in a horizontal plane. The lower nozzle is extended from below the central section of the substrate to below the peripheral section thereof. The upper nozzle includes a nozzle capable of discharging a chemical solution such as a dilute hydrofluoric acid to the upper surface of the substrate and a nozzle capable of discharging pure water or a rinse solution such as a mixed fluid of pure water and an inert gas to the upper surface of the substrate. The lower nozzle includes a large number of discharge ports that face the lower surface of the substrate and are capable of discharging the rinse solution to the lower surface of the substrate. The apparatus first discharges a chemical solution to the substrate from the upper and lower nozzles to perform a treatment with a chemical solution (chemical solution treatment). Subsequently, the apparatus performs a rinsing treatment by discharging a rinse solution from the nozzles, and then, rotates the substrate at high speed to perform a drying treatment of drying the substrate by draining out the liquid adhering to the substrate.
An airflow cutting across the lower nozzle and flowing in the direction of rotation of the substrate is formed below the substrate. The cross-section of the lower nozzle in the plane perpendicular to the radial direction of the substrate has a wing shape. More specifically, the lower surface of the lower nozzle is a horizontal surface extending in the radial direction of the substrate. The lower nozzle further includes an upper surface, which is extended parallel to the lower surface and is narrower than the lower surface, an upstream connecting surface that connects the ends upstream in the airflow in the width directions of the upper and lower surfaces, and a downstream connecting surface that connects the ends downstream in the airflow. The upstream connecting surface is much wider and has a gentler slope than the downstream connecting surface. The upstream connecting surface is curved while being recessed to the inside of the lower nozzle, whereas the downstream connecting surface is curved while projecting to the outside of the lower nozzle. The airflow generated through the rotation of the substrate is rectified to impinge upon the lower nozzle and then travel toward the lower surface of the substrate along the upstream connecting surface. In this case, the flow rate also increases thanks to the diaphragm effect. The chemical solution and the rinse solution, discharged from the lower nozzle to the lower surface of the substrate in the chemical solution treatment and the rinsing treatment, are diffused smoothly along the lower surface of the substrate through the airflow.
In such a general substrate treating apparatus, the treatment amount (such as an etching amount) in the thickness direction of the substrate varies greatly due to, for example, a change of about 0.1° C. to 0.2° C. in substrate temperature (treatment temperature). The substrate treating apparatus of Japanese Patent No. 5123122 has a problem: the apparatus has difficulty in achieving a desired treatment amount because the substrate temperature varies due to a temperature difference between the treatment solution emitted to the upper surface of the substrate and the fluid supplied to the lower surface of the substrate. For the above-mentioned substrate treating apparatus, the treatment amount such as an etching amount with a treatment solution may not be uniformized unless the temperature distribution in the radial direction of the substrate is made non-uniform, depending on the quality of a film formed on the substrate or the presence or absence of scanning at a treatment solution supply position. The substrate treating apparatus of Japanese Patent No. 5123122, however, has another problem: the apparatus performs temperature control for reducing a temperature difference between the central portion and the edge portion of the substrate, and thus, has difficulty in uniformizing the substrate treatment depending on the substrate treatment conditions. Further, the substrate treating apparatus suffers from an increasing apparatus manufacturing cost associated with an increased number of temperature control units, complicating temperature control.
In the substrate treating apparatus of Japanese Patent Application Laid-Open No. 2012-151439, the downstream connecting surface of the lower nozzle has a steep gradient, which makes it difficult for the airflow along the upstream connecting surface of the lower nozzle toward the lower surface of the substrate to flow along the downstream connecting surface after passing through the upper surface of the lower nozzle. For this reason, also after the draining treatment, the liquid such as the rinse solution adhering to the downstream connecting surface of the lower nozzle is not thoroughly drained out to be left. The remaining solution causes a problem: it triggers a watermark or particle when the treatment is performed with a different chemical solution or when another substrate is treated.
The substrate treating apparatus of Japanese Patent Application Laid-Open No. 2012-151439 needs to fix a one-end portion of the lower nozzle, which is below the central section of the substrate, and a support member, which is inserted through a cylindrical rotating spindle of a spin chuck holding the substrate, with screws or the like. In the one-end portion of the lower nozzle is provided a structure for fixing with a screw or the like. This allows the chemical solution to be easily left in the lower nozzle, particularly in the one-end portion, after the rinsing treatment. As a result, in the case where, for example, a plurality of chemical solutions are used in combination in the chemical solution treatment and the rinsing treatment in order, the action of a new chemical solution is damaged due to the remaining chemical solution.